Injector flask



sept. 26, 1944.

w, J. PRYOR ET Al..`

INJECTOR FLASK Filed May 2. 1941 2 Sheets-Sheet l 2 2 5 w o 1 7 1, u 7 w 5 wz 3 5 l@ 9 .M J 5 ZJ M i Y M 1M q u 7 0 o 1 2, m a a w e m W i 70 2 M )Ff f. fm n m L w/.f A 1 TF. T-K 4 Y... P' E u .J R m fm o R 2 6 w@ V.. O V. 6 uu R T .m m n P m .w ww @wl J. m H I I F w wm/ do a, m fw ..1 4@ 6 z 2 M n.

7 e S a. Z 5. www Z Patented Sept. 26, 1944 UNITED STATES PATENT OFFICE INJnoroa FLA-sn Walter J. Pryor, Cleveland, Ohio, and Edmond J. Franwick, Buffalo, N. Y., assigncrs to Hanau Engineering Company, Inc., Buffalo, N. Y., corporation of New York Application May 2, 1941, Serial N0. 391,612

6 Claims.

duction of a denture which will be an imperfect r flt in the mouth for which it has been designed. Moreover, if the plastic material, such as synthetic resins and rubber or other approved plastic substances, is not under constant pressure, a pulling strain would be caused to take place at the necks of the teeth which would result in the cracking of the teeth, and in some instances the cracking of the plate or body portion of the denture adjacent the teeth. Such strains or inherent stresses also have a tendency to cause lateral deflection of one or more of the teeth and thereby disturb the relation of the teeth to the denture base as originally intended and arranged in the wax.

As ordinarily practiced, excess denture mate-- rial is inserted in the mold or flask, the latter being closed with hand pressure, after which the mold is placed in a press and the parts thereof forced together. This requires excessive` pressure, causing thickened portions beyond that of the wax eliminated and disturbs the arrangement of the teeth for articulation as set up in wax, thereby creating fins at the edge or periphery of the denture and causing a dislocation of parts. The teeth are, therefore, no longer in the relation to the denture base or gums originally intended and asthey were arranged in the wax.

It is one of the objects of our invention to pro-7 vide an improved injector and injection mold or ilask for making articial dentures by means oi which the above-mentioned objections are entirely obviated.

A further object of our invention is to provide a mold or flask by means of which a highly condensed material is provided for the denture with out causing dislocation of the teeth, or distortion or malformation of any oi' the parts or surface areas ofthe denture.

Another object of our invention is to provide a denture mold or flask in which combined hand pressure is applied so as to exert force against the plastic material which, by reason of its nature, has a tendency to shrink, and utilizing constant strain or other automatic pressure to con-l dense the material andl augment the supply thereof to the cavity in which the denture is to be formed; the constant pressure thus provided and the augmented supply of plastic material furnished as required assuring a thoroughly condensed plastic composition incapable oi shrinking or of causing fractures of the teeth.

A further object of our invention is to provide a combined injector and mold or flask which is easily manipulated, inexpensive, comparatively simple in construction, and readily adjustable to meet any requirements in the production of artiflcial dentures.

With the above and other objects to appear hereinafter, our invention consists in the novel lfeatures of construction and in the arrangement and combination of Vparts to be hereinafter de'- scrlbed and more particularly pointed out in the subjoined claims.

In the drawings,

Fig. 1 is an elevation of our improved injector and injection mold or Ilask.

Fig. 2 is a vertical section taken on line 2 2, Fig. 3, the plunger-cylinder, however, being shown in elevation.

Fig. 3 is a vertical section taken on line 3 3,

Fig, 1, looking in the direction of the arrow cross:l

Fig. 10 is a vertical section of the lower' member or section of the flask showing the pre- :formed case invested therein and retained in posltion by means of plaster of Paris or other suit-- able investment material; the preformed case being so positioned that a line transversely` through the axial plane of the device Will be across the first molar region of the case.

lig. ll is a similar view showing an arched wax-sprue applied to the case, opposite ends of this sprue ,being attached to that portion of the case directly below the iirst molar teeth.

Fig.` l2 is a vertical section through the mold or nasi; showing-the manner of adjusting the pressure plunger or piston with respect to the sprue.

Fig. 13 is a view similar to Fig. 12, illustrating a step im the process of preparing the de- Vice for reception of the methyl-methacrylate or other plastic substance employed for forming the denture.

Fig. 14 is a vertical section through the flask after detaching the pressure-cylinder and its plunger or pieton, and after boiling out the wax of the case.

Fig. l5 is a similar view showing the mold or flask partly filled with the denture material.

Fig. 16 is a similar view 'showing additional denture material supplied to the mold or flask ready to be compressed by the piston or plunger under hand pressure.

Fig. 17 is a view similar to Fig. 16 with the injector or pressure element of the device attached to the plunger-cylinder. y

Referring now to the drawings by reference numerals, 2U designates the mold or flask considered as a whole. This flask may be formed in any suitable manner so long as it retains the essential parts of the mold or flask illustrated and it permits the use of a cylinder and piston or plunger applied as shown. The mold or flask preferably comprises a lower section 2|, a central or intermediate section 22, and a cover or top section 23. While we have shown the ilask somewhat of triangular formation in the drawings, it may be otherwise formed if desired. The lower section is dish-like in formation and comprises a bottom 24 and an upstanding or peripheral wall 25, the, upper edge of the latter being machined smooth and having the lower edge of the periph,

eral wall of the intermediate section 22 likewise finished, in firm contact therewith. This wall is split at 26; and at opposite sides of the line of separation thus formed, lugs 21, 28 are provided,

through one of which a. screw 29 is passed and into the other of which it is threaded. This screw may be termed an investment-releasing screw since when slightly unscrewed, the periph eral wall of the intermediate section becomes er:n panded or enlarged, for a. purpose to appear hereu inafter. The upper edge of the peripheral wall of this intermediate section ls also machined smooth and even, and the cover or top section 23 rests upon said edge. Bolts 30 are employed to fasten the three sections of the mold together.

As is common in flasks o this type. prynotches are provided in the wall of the flask for the purpose of facilitating the separation of the sections of the flask. These are, for example, shown at 3i, 32, Fig. 3, the pry-notch 3| being formed on the under side of the cover or upper section and pry-notch 32 in the wall oi the lower section at the upper edge thereof. The cover or upper section is also provided with the usual keyopenings 33 for keying the investment and for the escape of any surplus investment material.

On one side of the flask two sets of verticallyalined lugs 34 are formed, and in the lugs of the central or intermediate section 22, dowel pins 35 are driven with opposite ends projecting there-1 from and adapted to enter openings ist, ill' formed respectively in the lugs of the cover or upper sec tion 23 and the lower section 2l of the iiask, this being for the purpose of axially alining the sec tions so that when placed in superimposed relation, they will be accurately positioned for connecting them together by means of the bolts 30. A threaded opening 38 is formed in the cover or upper section, and into this is adjustably threaded an anchor in the form ci' a sleeve 39 which we utilize as and term a piston or plunger cylinder for the injector or pressure device employed.. This sleeve or cylinder has a hexagonal or other non-circular flange 40 at its upper end by means of which a wrench may be applied thereto for adjusting the same when found necessary, and in this sleeve is slidably fitted a pistonor plunger 4l having a head 42 at its upper end. A wing like nut 43 is applied to the sleeve or cylinder 39 and is designed to be clamped against the upper face of the cover or top section of the mold or flap when the cylinder is properly adjusted.

The reference numeral 44 designates what we term an injector frame. It is cast l? OthelWiSe formed in the shape of an elongated loop having a. header 45, side members 46 extending downwardly from said header, and a tailpiece or transverse bottom member 41 connecting the lower ends of said side members. The tail-piece 41 is provided with a notch 48 opening at one edge and designed to receive the upper end of the cylinder 39. The tail-piece may therefore be said to straddle the cylinder and the flange 40 at the .upper end of the latter lies in contact with the upper side of said tail-piece. The cylinder has an externally-threaded region extending from its lower end to a point near the flange, at which point the exterior diameter' of the cylinder is slightly enlarged, as at 49, to snugly t into the notch 48 formed in the tail-piece of the injector frame, thereby assuring a non-wobbling connection between the cylinder and the injector frame.

The side members 4E of the injector frame may be termed guide members, since they have guide ribs 50 formed along their inner sides. These guide ribs terminate in the same horizontal plane at their lower ends, but one of these is considerably shorter than the other so that their upper ends terminate in diilerent horizontal planes.

Within this injector frame we provide a. spring chamber 5I which comprises two hollow or cuplike members 52, 53, the open ends of which are in opposition, and these cup-like members are pro vided at diametrlcally-opposite points with guide grooves 54 which receive the guide ribs 5I on the injector frame. The closed lower end of the lower cuplike member 53 vis adapted to bear against the head 42 of the piston or plunger 4|, and between the two members and within the hollow portions thereof a helical spring 5l is iitted, the upper end of which bears against the upper wall of the upper member 52 and the lower end against the lower wall of the lower member 53. It will be apparent, therefore, that the upper cup-like member of this spring chamber is employed in inverted position so that the opposed cavities in the two cup-like members form a spring chamber in which the spring Il is confined under pressure.

56 is a pressure screw which has its lower end rotatably mounted in the end wall of the inverted upper cup-like member 52, and it is threaded through the header 45 of the injector frame and has a handle 51 pinned or otherwise secured to its upper end.

Since the space between the header 45 and the upper end of the short guide rib 50 on the injectorframe is greater than the length of either of the cup-like members of the spring` chamber, it will be clear that these members may be easily inserted in the injector frame when assembling the parts o1' the pressure or injector device. The spaces between the lower ends of the guide ribs 46 and the tail-piece or transverse bottom member 41 at the bottom of the injector frame are greater than the length oi the lower cup-like member of the spring chamber. Said member may therefore be removed from the injector frame after detaching the latter from the cylinder 39. Although the two members of the spring chamber are guided for vertical movement in the injector frame by means of the guide ribs 50 and guide grooves 54, We provide additional guides for the upper member 52 of the spring chamber, and for this purpose we increase the thickness of the walls of said cup-like member at diametrically opposite points, as best shown at 58, Figs. 4 and 7. In each of these thickened portions of the upper "vided as desired vesting the case and sprueing the same, the.

cup-like member, pin-holes These pin-holes are reduced in lower ends, as at 60, to form upwardly-facing shoulders therein, and in these pin-holes combined guide-pins and pressure or spring-indiare located, said pins or indicators having reduced intermediate portions 62 downwardly-facing shoulders adapted under to engage the upwardly-facing shoulders in the pin-holes. The shoulders serve as stops and limit the separating movement of the two members oi' the spring chamber, as will be hereinafter more particularly described. These pins are further reduced in diameter at their lower ends and threaded, as at 83, and these threaded lower ends are threaded into openings 64 formed in thickened portions l of the peripheral wall of the lower cup-like member of the spring chamber.

It will be apparent from the foregoing that the flask forms the base for the apparatus and all parts associated therewith are carried thereby. In this emclent device is provided in which the infecter parts can be easily attached and as readily detached from the iiask proper.

In the normal or operating relationship of parts these pins project above the upper end of the inverted upper cup-like member of the spring chamber, and the degree of extension of these pins indicates the degree of pressure exerted by the spring within said spring chamber. The pins may be graduated at their upper ends, if desired.

In the use of this invention a preformed waxed-up cast, designated by the numeral 86, is invested as low as possible in the lower section of the flask so that a line across the first molar region o1' the case will be directly below the axis of the piston or plunger Il, the crests of the ridges 61 of this case being somewhat above the upper edge of the confining wall of this flask section. This waxed-up cast, which is of the usual form, is surrounded by plaster, which becomes bonded thereto and to said wall, and this surrounding plaster 68 is smoothened at the top and preferably inclined downwardly 59 are formed. diameter at their case in the lower section of the flask, a roll of wax about three-sixteenths of an inch in diameter is arched across the case and luted in place Just below the iirst molar teeth to form an arched sprue 89 extending across the denture from right to left; the upper surface of this arched waxsprue being preferably slightly flattened with its crest or highest elevation in line or approximately in line with the occiusal surfaces of the teeth 10, but not above such level.

In thick or heavy cases, an additional wax- Additional sprues may be proor required. After thus incentral or intermediate section of the flask. with the investment-releasing screw 29 tightened, is placed over the lower section and the cover or the intermediate secpiston or plunger 4l are then adjusted with a view of positioning the latter so that its lower end touches the waxmanner a very compact and highly sprue 69 and the head l2 or the piston or plunger contacts the upper end of the cylinder 39, as shown in Fig. l2. The cylinder is then locked in adjusted position by tightening the wing locknut 43 against the flask cover, making certain that the head of the piston and the upper end of the cylinder remain in contact. After having thus adjusted the cylinder and its piston or plunger, the cover with the cylinder and plunger may be removed and the remaining portion of the flask filled with plaster as usual, but preferably with a view of facilitating later separation of the finished case from the investment, two separate mixes are used as follows: Plaster of Paris is poured into the flask to or approximately to the level indicated at 1I, Figs. 13 to 17, leaving the occlusal surfaces of the teeth 'l0 and the top of the arched wax-sprue uncovered, the crest of the wax-sprue having the plaster of Paris wiped away to expose the same.

is then completely filled with artificial stone, or

investing substance, after which the cover or upper section carrying the cylinder and piston as an assembly is placed upon the previously assembled portion of the flask so that full contact at all points is assured between the upper edge of the intermediate section and the under side of the cover or top section. When thus applying the cover or top section. the surplus investment material. such as the artificial stone referred to, ilnds escape through the key openings 33, the excess investment material forced through said key openings being wiped flush or substantially flush with the upper surface of the cover or top section. This cover or top section is held firmly in place, and by means of a linger, the piston or plunger is gently tapped so that its head rests against the upper end of the cylinder,

after which the piston, the cylinder, and the wing lock-nut are removed. boiled out and the mold cleaned in the customary manner. When the wax is boiled out, the mold will aippear as shown in Fig. 14, forming a cavity or cavities 12 and an arched passage or passages 13 where the wax-sprue or sprues previously appeared. This passage or C passages open into a vertical opening 14 previously formed around the lower end of the piston or plunger' when buildingy up the investment portion within the central or intermediate section of the flask. The vertical opening 'il is co-axial with the internally-threaded opening 38 in the cover or top section of the flask.

It is of course to be understood that the cavity orcavlties l2 extend through the area previously occupied by the wax constituting the roof and gum portions of the case, and after thel wax is thus boiled out, the

space between them 81 extending upwardly from the stone-composition or body portion of the case. The flask is thus prepared to receive the denture material.

It is also to be understood that the tinfoil commonly used in the practice of making dentures (not shown nor previously referred to herein), is next trimmed at the ends of the passage or passages 13 to provide connection between the cavity or cavities 'l2 which may truly be termed the mold, and the vertical opening 14 which may be termed a reservoir, The mold is then slightly hand packed with denture material. Cellophane which has been wetted and then dried in a towel, is placed between the central or intermediate section of the liask and the lower section, and the flask closed in a bench press to expel all excess material. The flask is again opened and after removing the Cellophane (a step in the process of making dentures commonly employed), more denture material is added if and where required. Any excess material which has been forced out of the cavity or cavities, more definitely referred to as the mold and the passage or passages i3, depending on whether one or more sprues had been employed, which will have been forced out of the mold on or beyond the shoulders of the case, will be removed so that the ask will be completely closed without effort. Under such conditions some plastic denture material will have entered the passage or passages 73 and probably the vertical opening or reservoir i4, which latter with the bore of the sleeve 3Q may be termed a feed passage.

The ilask is then bolted together as shown in Fig. 16, and the cylinder is again threaded into the threaded opening 38 in the cover or top secs tion of the flask until lt assumes its original pow sition which is controlled by the hardened lnvestment, the cylinder being locked securely by the wing lock-nut 43. The cylinder and any void existing in the vertical opening or reservoir l is next filled with sulilcient denture mate to cause the piston, when inserted into the cy.

and pressed. down. by hand, to entend. upraf' idly about one inch above the cylinder, illustrated in Fig. 16.

With the piston thus arranged in the cylinder, the pressure device or injector is attached to the upper -end of the cylinder in the manner previ.

ously described. The pressure screw t ls then tightened until the cupdike members of the spring chamber 5l are spaced a deiinlte distance apart, say for example 2 min, lliis causes the piston to be forced downwardly in the cylinder, and in 'some instances into the ci the investment; and for the sake of clearness we prefer to consider the interior ci the cylinder and the vertical opening 'It in the investment as a complete reservoir for. the reception of the plastic denture material. The piston will be pressed into this reservoir so considered, and the spring within the spring chamber will hold the piston under sustained pressure during curing.

It ls to be noted that when the pressure screw ls threaded downwardly in the injector trane and the pressurespring is thereby further corn-1 pressed within the spring chamber, the pins or indicators tl will extend upwardly above the upper end of' the upper inverted cup-dike member of said spring chamber, and the degree ci enten sion` will denitely determine the degree ci presn sure under which the spring is placed. Should the pressure thus exerted result in forcing the piston down so that the head ci the same comes close to the upper end ofthe cylinder, say` ior example one-eighth of an inch, the spring presez sure is released, the piston removed from its cylinder, and more denture material added to the reservoir, after which pressure is again applied in the manner stated. The flask is then allowed to stand a few minutes, and if the spring cham bers have become separated,l the pressure screw is again tightened until the 2 mm. space or approximately so, is re-established between the two cup-like members of the spring chamber.

The flask. with the injector or pressure device Cil the case polished in the usual manner.

attached is next placed in a. pan of water so that lthe lower one-third of the flask is immersed.

mold and the operator ls free to attend to other' work. Should he, however, upon examination of the device after having devoted his time to other work, find the indicator pinsto be flush with the top surface of the upper member of the spring chamber, he will realize that spring pressure on the denture material is entirely eliminated.

Burlng curing, the indicator pins should at all times show above the upper end of the inverted cuplike member of the spring chamber, and if necessary, the pressure screw is to be tightened until these indicators extend at least one-quarter of an inch.

After curing the case, or in other words, after vulcanizing the denture material, it is allowed to cool and the injector is then detached from the flask by loosening or unthreadlng the pressure screw. The piston and cylinder are then removed from the flask. They may bev removed by aid of the wing lock nut 43 which, when screwed against the shoulder formed by the enlarged portion of the cylinder directly above lts threaded region, will serve as a handle, or the injector may be employed to serve as a. handle in removing the cylinder and piston from the flask by threading the wing lock nut I3 against the tall piece or transverse bottom member 41 of the injector frame.

a suitable tool ls then placed in the pryingnotch 32 at the dividing line between the bottom and central or intermediate sections o! the ask to lift the case from the bottom section. The cover or top section ls then removed in the same manner by inserting a suitable tool in the pryingnotch 3l. This leaves the case entirely attached to the middle or intermediate section, whlch ls then expanded by loosening the investment-releasing screw 29 sufficiently to permit the easy removal of the finished case therefrom;

The denture is then removed from the investment and cleaned. The sprue formed on the denture by reason of lling the sprue passage 1I with denture material is carefully cut oi! yand Clear palate cases and partial dentures are formed in the ilaskunder methods accepted by the proiesslon and need not herein be described since this will be quite clear to those skilled in the art after the description given with reference to the mak,- lng of a lull denture.

Having thus described our invention, what we claim is:

l.. ln a molding apparatus ot the character described, a flask having a mold formed therein provided with a cavity conforming to the article to be molded, a cylinder adjustably threaded into one oi the walls of said flask and having a material reservoir connecting the same with said cavity, said cavity adapted to receive material to be molded and said reservoir to receive a quantity of such material, a piston movable within said cylinder and limited in its inward movement by the adjustment made for said cylinder, and an injector device removably applied to said cylm inder and having an elongated frame, a pressure screw threaded into said frame, an expansible and contractible spring housing against which said pressure screw acts and a spring within said housing, said spring housing when expanding through the medium of said spring exerting pressure against said piston and said spring being placed under compression by said screw.

2. In a molding apparatus of the character described, a ilask having a mold formed therein provided with a cavity conforming to the article to be molded and serving as a base for the apparatus, a cylinder extending from a wall o f said ask, said cavity adapted to receive 4a quantity o'f material to be molded, a piston movable within said cylinder, an injector frame removably secured to said cylinder in unchanging relation thereto and having a spring-pressure device slidable therein comprising two opposed cup-shaped members and a spring within said members, one of said cup-shaped members bearing against said piston. and a pressure screw threaded into said frame and exerting pressure against the other of saidcup-shaped members to compress the spring within said members. g

3. In a molding apparatus of the character described, a flask having a screw-threaded opening in one of its walls and a mold formed therein provided with a cavity conforming to the article to be molded, a cylinder adjustably threaded into said screw-threaded opening and extending any selected distance outwardly from the wall of the flask into which it is threaded, the interior of said cylinder'beingin conduit-connection with said cavity and forming with said connection a material reservoir, said cavity adapted to receive material to be molded and said reservoir to receive a quantity of such material for supplying any deficiency of material that may exist in the cavity, a piston inserted in said cylinder from its outer end and adapted to bear against the material in said reservoir, an injector device removably applied to said cylinder in unchanging relation thereto and comprising an elongated looplike frame. a pressure-screw threaded through the outer end of said frame, and a spring-pressure device in said frame interposed between said pressure-screw and said piston, said pressure screw placing said spring-pressure device under tension and incidentally applying initial pressure to said piston to force material from said reservoir into said cavity and said spring-pressure device exerting continued pressure on said piston under pressure exerted by said pressure screw to maintain the material within said reservoir and said cavity under constant pressure.

4. In a molding apparatus of the character' described, a flask having a screw-threaded opening in one oi' its walls and a mold formed therein provided with a cavity conforming to the denture to 'be molded, a cylinder adjustably threaded into said screw-threaded opening and extending any predetermined distance outwardly from the wall of the ask into which it is threaded. said cylinder having an enlargement at its upper end forming a downwardly-facing exterior shoulder thereon, the interior of said cylinder being in conduit-connection with said cavity by a passage serving with said cylinder as a material reservoir, said cavity adapted to receive material to be molded and said reservoir to receive a quantity of such material for supplying any deiiciency of material that may exist in the cavity, a piston inserted in said cylinder from its outer end and adapted to bear against the material in said reservoir, an injector device removably applied to said cylinder engaging the underside of the shoulder thereon and comprising an elongated looplike frame extending outwardly from said cylinder, a pressure-screw threaded through the outer end of said frame, and a spring-pressure device in said frame guided for longitudinal movement therein, said spring-pressure device comprising two opposed cup-like members forming a spring chamber and a helical spring within said members, one of said cup-like members being engaged by said pressure screw and the other being in contact with said piston, said pressurescrew placing said spring-pressure device under tension and incidentally applying initial pressure to said piston through said spring-pressure device to force material from said reservoir into said cavity and said spring-pressure device exerting continued pressure on said piston to maintain material within said reservoir and said cavity under constant pressure.

5. An injector device for flasks for molding dentures. comprising a loop-like frame having spaced-apart side members and adapted to be attached to a flask having an injector piston extending therefrom, a pressure-screw threaded through one end of said frame, and a springpressure device comprising two cup-like members having their open ends in opposition to form a spring chamber, arid a spring within said chambei-'bearing at opposite ends against the end walls of said cup-like members, said cup-like members and said side members having co-acting guide elements to guide said cup-like members along said frame, and prevent turning of said members, one of said cup-like members being moved along said guide elements by said pressure-screw and the other of said cup-like members being adapted for contact with said piston.

6. In a molding apparatus of the character described, a flask having a mold formed therein provided with a cavity conforming to the denture to be molded and a passage leading outwardly from said cavity, a piston slidable in said passage, an injector-device in association with said flask comprising a frame having two spacedapart cup-like members therein arranged with their open ends in opposition to form a spring chamber exerting pressure against said piston, means for guiding said cup-like members for movement in said frame and for preventing rotative movement thereof, a spring within said spring chamber, hand-pressure means for compressing said spring within its chamber against the resistance oil'ered by said piston while moving said cup-like members into closer proximity to each other, one of said cup-like members having pins projecting from itsl open end at diametrically-opposite points and the other having pin holes extending therethrough to receive said pins, said pins being adapted to project from the outer end of said last-mentioned member when said spring is under compression to indicate the approximate compression of the same.

WALTER J. PRYOR. EDMOND J. FRANWICK. 

